1. Field of the Disclosed Embodiments
The disclosure relates to air traffic trajectory synchronization, in particular to the synchronizing of distinct trajectories predicted by a plurality of systems.
2. Introduction
In trajectory based operations (TBO), air-ground and ground-ground interoperability and trajectory synchronization among the various systems is required since each of these systems rely on an accurate prediction of the flight path in four dimensions (4D trajectory or 4DT). Without proper synchronization, the Air Traffic Control (ATC) and Air Traffic Management (ATM) of the airspace is forced to add significant uncertainty into its prediction of the aircraft trajectory, thus decreasing the potential capacity of the available airspace and the efficiency of operations. The uncertainty that results from air-ground and ground-ground trajectory discrepancies also leads to non-optimal tactical intervention. The goal of air-ground (or ground-ground) trajectory synchronization is to produce trajectories in disparate systems whose discrepancies are operationally insignificant, increasing the likelihood of flying the planned conflict-free and business-preferred trajectories. In addition, if conditions change in the ground requiring alternative trajectories (i.e., projecting for conflict resolution or schedule management, for instance), then the ATC/ATM systems have to be able to independently build new trajectories that are compatible with user preferences and with the requirements of the Flight Management System (FMS) on board the aircraft.
In the field of flight management systems (FMSs), the technical problem to be solved is related to the use by the ground of predictions calculated by the FMS along the flight plan (location, altitude, speed, fuel, time of passage, for each point on the flight plan). In recent studies, it emerged that a significant improvement in capacity and safety for future ATM systems lay on the one hand in the collaboration between the Air Navigation Service Provider (ANSP) and onboard (aircraft) operators, in particular the synchronization of route and flight data, and on the other hand in the accuracy of the predicted trajectories.
The ground-based operators and supporting automation tools can use the predictions issued by aircraft to organize the traffic, balance the traffic load among each control sector, anticipate the dynamic control sector segmentations and groupings, sequence the aircraft more effectively in the terminal procedures, and lastly be able to deploy an end-to-end ATM system (“4D” and “Gate to Gate” concepts).
All these operations require both regular synchronization and precision in trajectory forecasts carried out on the ground and on board. One of the main challenges to Trajectory Based Operations (TBO) is interoperability and coordination among systems (air-ground and ground-ground). It is foreseen that a primary means to respond to this
Challenge is to provide a common view of operations as provided by synchronized trajectories. 4DTs provide the basis for both strategic planning and tactical operations, and as such they are key enablers of TBO. On board the aircraft, the FMS uses a trajectory for closed-loop guidance by way of the automatic flight control system (AFCS). In ground systems, the trajectory provides the information that is required for planning and for performing critical air traffic control and traffic flow management functions, such as: scheduling, conflict prediction, intra-sector hand off, separation management and conformance monitoring. With such a vast range of uses, the unique set of trajectory requirements (which at times may be contradictory) applicable to each function cannot be met in an efficient manner by simply sharing a common trajectory. A trajectory used to guide the aircraft requires a different level of fidelity than a trajectory used to estimate sector load in the ground a few hours into the future.
Previous studies identified various Trajectory Synchronization approaches, including: Flight Intent synchronization, Aircraft Intent (AI) synchronization, Behavior Model synchronization, Predicted Trajectory synchronization. Flight intent is primarily the information carried by the flight plan but it is insufficient for accurate synchronization because it does not contain enough information to build from it an unambiguous rendition of the flight path in 4D (i.e. multiple dissimilar trajectories can be generated from the same flight plan). Aircraft intent-based trajectory synchronization relies on using the FMS provided AI so it lacks all of the knowledge available by the ground system. Behavior Model data consists of a list of the maneuvers that the aircraft needs to execute in order to follow the flight plan, thus it is similar to aircraft intent data except that the information is expressed more abstractly. Synchronization using aircraft intent or behavior model data does not account for differences in weather forecast models and aircraft performance models, therefore could result in significantly different 4D predictions. The last approach, Predicted Trajectory synchronization consists of down-linking the FMS predicted 4D trajectory (for example via Automatic Dependent Surveillance-Contract (ADS-C) Extended Projected Profile (EPP) reports) and using it “as is” by the ground systems. This approach is limited by the fact that the FMS 4D trajectory is a prediction for current conditions and constraints only, and if conditions change in the ground that require building alternative trajectories the FMS 4D-trajectory has to be discarded and a completely new trajectory has to be built on the ground system, opening the possibility for breaking synchronization.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification there is need in the art for a system and method that synchronizes trajectories from disparate systems.